/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright by The HDF Group.                                               *
 * Copyright by the Board of Trustees of the University of Illinois.         *
 * All rights reserved.                                                      *
 *                                                                           *
 * This file is part of HDF5.  The full HDF5 copyright notice, including     *
 * terms governing use, modification, and redistribution, is contained in    *
 * the files COPYING and Copyright.html.  COPYING can be found at the root   *
 * of the source code distribution tree; Copyright.html can be found at the  *
 * root level of an installed copy of the electronic HDF5 document set and   *
 * is linked from the top-level documents page.  It can also be found at     *
 * http://hdfgroup.org/HDF5/doc/Copyright.html.  If you do not have          *
 * access to either file, you may request a copy from help@hdfgroup.org.     *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/****************/
/* Module Setup */
/****************/

#define H5F_PACKAGE		/*suppress error about including H5Fpkg	  */

/* Interface initialization */
#define H5_INTERFACE_INIT_FUNC	H5F_init_super_interface


/***********/
/* Headers */
/***********/
#include "H5private.h"		/* Generic Functions			*/
#include "H5Eprivate.h"		/* Error handling		  	*/
#include "H5Fpkg.h"             /* File access				*/
#include "H5FDprivate.h"	/* File drivers				*/
#include "H5Iprivate.h"		/* IDs			  		*/
#include "H5MFprivate.h"	/* File memory management		*/
#include "H5MMprivate.h"	/* Memory management			*/
#include "H5Pprivate.h"		/* Property lists			*/
#include "H5SMprivate.h"        /* Shared Object Header Messages        */


/****************/
/* Local Macros */
/****************/

/* Superblock sizes for various versions */
#define H5F_SIZEOF_CHKSUM 4     /* Checksum size in the file */

/* Fixed-size portion at the beginning of all superblocks */
#define H5F_SUPERBLOCK_FIXED_SIZE ( H5F_SIGNATURE_LEN                   \
        + 1) /* superblock version */

/* Macros for computing variable-size superblock size */
#define H5F_SUPERBLOCK_VARLEN_SIZE_COMMON                               \
        (2  /* freespace, and root group versions */			\
        + 1 /* reserved */                                              \
        + 3 /* shared header vers, size of address, size of lengths */  \
        + 1 /* reserved */                                              \
        + 4 /* group leaf k, group internal k */                        \
        + 4) /* consistency flags */
#define H5F_SUPERBLOCK_VARLEN_SIZE_V0(f)                                \
        ( H5F_SUPERBLOCK_VARLEN_SIZE_COMMON /* Common variable-length info */ \
        + H5F_SIZEOF_ADDR(f) /* base address */                         \
        + H5F_SIZEOF_ADDR(f) /* <unused> */				\
        + H5F_SIZEOF_ADDR(f) /* EOF address */                          \
        + H5F_SIZEOF_ADDR(f) /* driver block address */                 \
        + H5G_SIZEOF_ENTRY(f)) /* root group ptr */
#define H5F_SUPERBLOCK_VARLEN_SIZE_V1(f)                                \
        ( H5F_SUPERBLOCK_VARLEN_SIZE_COMMON /* Common variable-length info */ \
        + 2 /* indexed B-tree internal k */                             \
        + 2 /* reserved */                                              \
        + H5F_SIZEOF_ADDR(f) /* base address */                         \
        + H5F_SIZEOF_ADDR(f) /* <unused> */				\
        + H5F_SIZEOF_ADDR(f) /* EOF address */                          \
        + H5F_SIZEOF_ADDR(f) /* driver block address */                 \
        + H5G_SIZEOF_ENTRY(f)) /* root group ptr */
#define H5F_SUPERBLOCK_VARLEN_SIZE_V2(f)                                \
        ( 2 /* size of address, size of lengths */                      \
        + 1 /* consistency flags */                                     \
        + H5F_SIZEOF_ADDR(f) /* base address */                         \
        + H5F_SIZEOF_ADDR(f) /* superblock extension address */         \
        + H5F_SIZEOF_ADDR(f) /* EOF address */                          \
        + H5F_SIZEOF_ADDR(f) /* root group object header address */     \
        + H5F_SIZEOF_CHKSUM) /* superblock checksum (keep this last) */
#define H5F_SUPERBLOCK_VARLEN_SIZE(v, f) (				\
        (v == 0 ? H5F_SUPERBLOCK_VARLEN_SIZE_V0(f) : 0)			\
        + (v == 1 ? H5F_SUPERBLOCK_VARLEN_SIZE_V1(f) : 0)               \
        + (v == 2 ? H5F_SUPERBLOCK_VARLEN_SIZE_V2(f) : 0))

/* Total size of superblock, depends on superblock version */
#define H5F_SUPERBLOCK_SIZE(v, f) ( H5F_SUPERBLOCK_FIXED_SIZE           \
        + H5F_SUPERBLOCK_VARLEN_SIZE(v, f))

/* Driver info block macros */
#define H5F_DRVINFOBLOCK_HDR_SIZE 16

/* Maximum size of super-block buffers */
#define H5F_MAX_SUPERBLOCK_SIZE  134
#define H5F_MAX_DRVINFOBLOCK_SIZE  1024


/******************/
/* Local Typedefs */
/******************/


/********************/
/* Package Typedefs */
/********************/


/********************/
/* Local Prototypes */
/********************/
static herr_t H5F_super_ext_create(H5F_t *f, hid_t dxpl_id, H5O_loc_t *ext_ptr);
static herr_t H5F_super_ext_open(H5F_t *f, H5O_loc_t *ext_ptr);
static herr_t H5F_super_ext_close(H5F_t *f, H5O_loc_t *ext_ptr);


/*********************/
/* Package Variables */
/*********************/


/*****************************/
/* Library Private Variables */
/*****************************/


/*******************/
/* Local Variables */
/*******************/


/*--------------------------------------------------------------------------
NAME
   H5F_init_super_interface -- Initialize interface-specific information
USAGE
    herr_t H5F_init_super_interface()

RETURNS
    Non-negative on success/Negative on failure
DESCRIPTION
    Initializes any interface-specific data or routines.  (Just calls
    H5F_init() currently).

--------------------------------------------------------------------------*/
static herr_t
H5F_init_super_interface(void)
{
    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5F_init_super_interface)

    FUNC_LEAVE_NOAPI(H5F_init())
} /* H5F_init_super_interface() */


/*-------------------------------------------------------------------------
 * Function:	H5F_locate_signature
 *
 * Purpose:	Finds the HDF5 superblock signature in a file.	The signature
 *		can appear at address 0, or any power of two beginning with
 *		512.
 *
 * Return:	Success:	The absolute format address of the signature.
 *
 *		Failure:	HADDR_UNDEF
 *
 * Programmer:	Robb Matzke
 *		Friday, November  7, 1997
 *
 *-------------------------------------------------------------------------
 */
haddr_t
H5F_locate_signature(H5FD_t *file, hid_t dxpl_id)
{
    haddr_t	    addr, eoa;
    uint8_t	    buf[H5F_SIGNATURE_LEN];
    unsigned	    n, maxpow;
    haddr_t         ret_value;       /* Return value */

    FUNC_ENTER_NOAPI_NOINIT(H5F_locate_signature)

    /* Find the least N such that 2^N is larger than the file size */
    if(HADDR_UNDEF == (addr = H5FD_get_eof(file)) || HADDR_UNDEF == (eoa = H5FD_get_eoa(file, H5FD_MEM_SUPER)))
	HGOTO_ERROR(H5E_IO, H5E_CANTINIT, HADDR_UNDEF, "unable to obtain EOF/EOA value")
    for(maxpow = 0; addr; maxpow++)
        addr >>= 1;
    maxpow = MAX(maxpow, 9);

    /*
     * Search for the file signature at format address zero followed by
     * powers of two larger than 9.
     */
    for(n = 8; n < maxpow; n++) {
	addr = (8 == n) ? 0 : (haddr_t)1 << n;
	if(H5FD_set_eoa(file, H5FD_MEM_SUPER, addr + H5F_SIGNATURE_LEN) < 0)
	    HGOTO_ERROR(H5E_IO, H5E_CANTINIT, HADDR_UNDEF, "unable to set EOA value for file signature")
	if(H5FD_read(file, dxpl_id, H5FD_MEM_SUPER, addr, (size_t)H5F_SIGNATURE_LEN, buf) < 0)
	    HGOTO_ERROR(H5E_IO, H5E_CANTINIT, HADDR_UNDEF, "unable to read file signature")
	if(!HDmemcmp(buf, H5F_SIGNATURE, (size_t)H5F_SIGNATURE_LEN))
            break;
    } /* end for */

    /*
     * If the signature was not found then reset the EOA value and return
     * failure.
     */
    if(n >= maxpow) {
	(void)H5FD_set_eoa(file, H5FD_MEM_SUPER, eoa); /* Ignore return value */
	HGOTO_ERROR(H5E_IO, H5E_CANTINIT, HADDR_UNDEF, "unable to find a valid file signature")
    } /* end if */

    /* Set return value */
    ret_value = addr;

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5F_locate_signature() */


/*-------------------------------------------------------------------------
 * Function:    H5F_super_ext_create
 *
 * Purpose:     Create the superblock extension
 *
 * Return:      Success:        non-negative on success
 *              Failure:        Negative
 *
 * Programmer:  Vailin Choi; Feb 2009
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5F_super_ext_create(H5F_t *f, hid_t dxpl_id, H5O_loc_t *ext_ptr)
{
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_NOAPI_NOINIT(H5F_super_ext_create)

    /* Sanity check */
    HDassert(f);
    HDassert(ext_ptr);
    HDassert(!H5F_addr_defined(f->shared->extension_addr));

    H5O_loc_reset(ext_ptr);
    if(H5O_create(f, dxpl_id, 0, H5P_GROUP_CREATE_DEFAULT, ext_ptr) < 0)
	HGOTO_ERROR(H5E_OHDR, H5E_CANTCREATE, FAIL, "unable to create superblock extension")

    /* Record the address of the superblock extension */
    f->shared->extension_addr = ext_ptr->addr;

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* H5F_super_ext_create() */


/*-------------------------------------------------------------------------
 * Function:    H5F_super_ext_open
 *
 * Purpose:     Open an existing superblock extension
 *
 * Return:      Success:        non-negative on success
 *              Failure:        Negative
 *
 * Programmer:  Vailin Choi; Feb 2009
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5F_super_ext_open(H5F_t *f, H5O_loc_t *ext_ptr)
{
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_NOAPI_NOINIT(H5F_super_ext_open)

    /* Sanity check */
    HDassert(f);
    HDassert(ext_ptr);
    HDassert(H5F_addr_defined(f->shared->extension_addr));

    /* Set up "fake" object location for superblock extension */
    H5O_loc_reset(ext_ptr);
    ext_ptr->file = f;
    ext_ptr->addr = f->shared->extension_addr;

    /* Open the superblock extension object header */
    if(H5O_open(ext_ptr) < 0)
	HGOTO_ERROR(H5E_OHDR, H5E_CANTOPENFILE, FAIL, "unable to open superblock extension")

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* H5F_super_ext_open() */


/*-------------------------------------------------------------------------
 * Function:   H5F_super_ext_close
 *              
 * Purpose:    Close superblock extension
 *
 * Return:     Success:        non-negative on success
 *             Failure:        Negative
 *
 * Programmer:  Vailin Choi; Feb 2009
 *
 *-------------------------------------------------------------------------
 */
static herr_t 
H5F_super_ext_close(H5F_t *f, H5O_loc_t *ext_ptr)
{
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_NOAPI_NOINIT(H5F_super_ext_close)

    /* Sanity check */
    HDassert(f);
    HDassert(ext_ptr);

    /* Twiddle the number of open objects to avoid closing the file. */
    f->nopen_objs++;
    if(H5O_close(ext_ptr) < 0)
        HGOTO_ERROR(H5E_OHDR, H5E_CANTRELEASE, FAIL, "unable to close superblock extension")
    f->nopen_objs--;

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* H5F_super_ext_close() */


/*-------------------------------------------------------------------------
 * Function:    H5F_super_read
 *
 * Purpose:     Reads the superblock from the file or from the BUF. If
 *              ADDR is a valid address, then it reads it from the file.
 *              If not, then BUF must be non-NULL for it to read from the
 *              BUF.
 *
 * Return:      Success:        SUCCEED
 *              Failure:        FAIL
 *
 * Programmer:  Bill Wendling
 *              wendling@ncsa.uiuc.edu
 *              Sept 12, 2003
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5F_super_read(H5F_t *f, hid_t dxpl_id)
{
    uint8_t             sbuf[H5F_MAX_SUPERBLOCK_SIZE];     /* Buffer for superblock */
    H5P_genplist_t     *c_plist;            /* File creation property list  */
    H5F_file_t         *shared;             /* shared part of `file'        */
    H5FD_t             *lf;                 /* file driver part of `shared' */
    haddr_t             abs_super_addr;     /* Absolute offset of superblock in file */
    haddr_t             stored_eoa;         /*relative end-of-addr in file  */
    haddr_t             eof;                /*end of file address           */
    size_t              sizeof_addr;        /* Size of offsets in the file (in bytes) */
    size_t              sizeof_size;        /* Size of lengths in the file (in bytes) */
    const size_t        fixed_size = H5F_SUPERBLOCK_FIXED_SIZE; /*fixed sizeof superblock   */
    size_t              variable_size;      /*variable sizeof superblock    */
    uint8_t            *p;                  /* Temporary pointer into encoding buffer */
    unsigned            super_vers;         /* Superblock version          */
    herr_t              ret_value = SUCCEED;

    FUNC_ENTER_NOAPI(H5F_super_read, FAIL)

    /* Short cuts */
    shared = f->shared;
    lf = shared->lf;

    /* Get the shared file creation property list */
    if(NULL == (c_plist = (H5P_genplist_t *)H5I_object(shared->fcpl_id)))
        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "can't get property list")

    /* Find the superblock */
    if(HADDR_UNDEF == (abs_super_addr = H5F_locate_signature(lf, dxpl_id)))
        HGOTO_ERROR(H5E_FILE, H5E_NOTHDF5, FAIL, "unable to find file signature")

    /* Read fixed-size portion of the superblock */
    p = sbuf;
    if(H5FD_set_eoa(lf, H5FD_MEM_SUPER, abs_super_addr + fixed_size) < 0)
        HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "set end of space allocation request failed")
    if(H5FD_read(lf, dxpl_id, H5FD_MEM_SUPER, abs_super_addr, fixed_size, p) < 0)
        HGOTO_ERROR(H5E_FILE, H5E_READERROR, FAIL, "unable to read superblock")

    /* Skip over signature (already checked when locating the superblock) */
    p += H5F_SIGNATURE_LEN;

    /* Superblock version */
    super_vers = *p++;
    if(super_vers > HDF5_SUPERBLOCK_VERSION_LATEST)
        HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad superblock version number")
    if(H5P_set(c_plist, H5F_CRT_SUPER_VERS_NAME, &super_vers) < 0)
        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set superblock version")

    /* Sanity check */
    HDassert(((size_t)(p - sbuf)) == fixed_size);

    /* Determine the size of the variable-length part of the superblock */
    variable_size = H5F_SUPERBLOCK_VARLEN_SIZE(super_vers, f);
    HDassert(variable_size > 0);
    HDassert(fixed_size + variable_size <= sizeof(sbuf));

    /* Read in variable-sized portion of superblock */
    if(H5FD_set_eoa(lf, H5FD_MEM_SUPER, abs_super_addr + fixed_size + variable_size) < 0)
        HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "set end of space allocation request failed")
    if(H5FD_read(lf, dxpl_id, H5FD_MEM_SUPER, abs_super_addr + fixed_size, variable_size, p) < 0)
        HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to read superblock")

    /* Check for older version of superblock format */
    if(super_vers < HDF5_SUPERBLOCK_VERSION_2) {
        uint32_t	status_flags;	    /* File status flags	   */
        unsigned        btree_k[H5B_NUM_BTREE_ID];  /* B-tree internal node 'K' values */
        unsigned        sym_leaf_k;         /* Symbol table leaf node's 'K' value */

        /* Freespace version (hard-wired) */
        if(HDF5_FREESPACE_VERSION != *p++)
            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad free space version number")

        /* Root group version number (hard-wired) */
        if(HDF5_OBJECTDIR_VERSION != *p++)
            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad object directory version number")

        /* Skip over reserved byte */
        p++;

        /* Shared header version number (hard-wired) */
        if(HDF5_SHAREDHEADER_VERSION != *p++)
            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad shared-header format version number")

        /* Size of file addresses */
        sizeof_addr = *p++;
        if(sizeof_addr != 2 && sizeof_addr != 4 &&
                sizeof_addr != 8 && sizeof_addr != 16 && sizeof_addr != 32)
            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad byte number in an address")
        if(H5P_set(c_plist, H5F_CRT_ADDR_BYTE_NUM_NAME, &sizeof_addr) < 0)
            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set byte number in an address")
        shared->sizeof_addr = sizeof_addr;  /* Keep a local copy also */

        /* Size of file sizes */
        sizeof_size = *p++;
        if(sizeof_size != 2 && sizeof_size != 4 &&
                sizeof_size != 8 && sizeof_size != 16 && sizeof_size != 32)
            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad byte number for object size")
        if(H5P_set(c_plist, H5F_CRT_OBJ_BYTE_NUM_NAME, &sizeof_size) < 0)
            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set byte number for object size")
        shared->sizeof_size = sizeof_size;  /* Keep a local copy also */

        /* Skip over reserved byte */
        p++;

        /* Various B-tree sizes */
        UINT16DECODE(p, sym_leaf_k);
        if(sym_leaf_k == 0)
            HGOTO_ERROR(H5E_FILE, H5E_BADRANGE, FAIL, "bad symbol table leaf node 1/2 rank")
        if(H5P_set(c_plist, H5F_CRT_SYM_LEAF_NAME, &sym_leaf_k) < 0)
            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set rank for symbol table leaf nodes")
        shared->sym_leaf_k = sym_leaf_k;    /* Keep a local copy also */

        /* Need 'get' call to set other array values */
        if(H5P_get(c_plist, H5F_CRT_BTREE_RANK_NAME, btree_k) < 0)
            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get rank for btree internal nodes")
        UINT16DECODE(p, btree_k[H5B_SNODE_ID]);
        if(btree_k[H5B_SNODE_ID] == 0)
            HGOTO_ERROR(H5E_FILE, H5E_BADRANGE, FAIL, "bad 1/2 rank for btree internal nodes")
        /*
         * Delay setting the value in the property list until we've checked
         * for the indexed storage B-tree internal 'K' value later.
         */

        /* File status flags (not really used yet) */
        UINT32DECODE(p, status_flags);
        HDassert(status_flags <= 255);
        shared->status_flags = (uint8_t)status_flags;
        if(shared->status_flags & ~H5F_SUPER_ALL_FLAGS)
            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad flag value for superblock")

        /*
         * If the superblock version # is greater than 0, read in the indexed
         * storage B-tree internal 'K' value
         */
        if(super_vers > HDF5_SUPERBLOCK_VERSION_DEF) {
            UINT16DECODE(p, btree_k[H5B_CHUNK_ID]);
            /* Reserved bytes are present only in version 1 */
            if(super_vers == HDF5_SUPERBLOCK_VERSION_1)
                p += 2;   /* reserved */
        } /* end if */
        else
            btree_k[H5B_CHUNK_ID] = HDF5_BTREE_CHUNK_IK_DEF;

        /* Set the B-tree internal node values, etc */
        if(H5P_set(c_plist, H5F_CRT_BTREE_RANK_NAME, btree_k) < 0)
            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set rank for btree internal nodes")
        HDmemcpy(shared->btree_k, btree_k, sizeof(unsigned) * (size_t)H5B_NUM_BTREE_ID);    /* Keep a local copy also */

        /* Remainder of "variable-sized" portion of superblock */
        H5F_addr_decode(f, (const uint8_t **)&p, &shared->base_addr/*out*/);
        H5F_addr_decode(f, (const uint8_t **)&p, &shared->extension_addr/*out*/);
        H5F_addr_decode(f, (const uint8_t **)&p, &stored_eoa/*out*/);
        H5F_addr_decode(f, (const uint8_t **)&p, &shared->driver_addr/*out*/);

        /* Decode the symbol table entry */
        if(H5G_root_ent_decode(f, (const uint8_t **)&p) < 0)
            HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to read root symbol entry")

        /*
         * Check if superblock address is different from base address and
         * adjust base address and "end of address" address if so.
         */
        if(!H5F_addr_eq(abs_super_addr, shared->base_addr)) {
            /* Check if the superblock moved earlier in the file */
            if(H5F_addr_lt(abs_super_addr, shared->base_addr))
                stored_eoa -= (shared->base_addr - abs_super_addr);
            else
                /* The superblock moved later in the file */
                stored_eoa += (abs_super_addr - shared->base_addr);

            shared->base_addr = abs_super_addr;
        } /* end if */

        /* Set the base address for the file in the VFD now, after adjusting
         *  space for possible offsets of the HDF5 data in the file.
         */
        if(H5FD_set_base_addr(lf, shared->base_addr) < 0)
            HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "failed to set base address for file driver")

        /* This step is for h5repart tool only. If user wants to change file driver
         *  from family to sec2 while using h5repart, set the driver address to
         *  undefined to let the library ignore the family driver information saved
         *  in the superblock.
         */
        if(shared->fam_to_sec2)
            shared->driver_addr = HADDR_UNDEF;

        /* Decode the optional driver information block */
        if(H5F_addr_defined(shared->driver_addr)) {
            uint8_t dbuf[H5F_MAX_DRVINFOBLOCK_SIZE];     /* Buffer for driver info block */
            char drv_name[9];       /* Name of driver */
            unsigned drv_vers;      /* Version of driver info block */
            size_t drv_variable_size; /* Size of variable-length portion of driver info block, in bytes */

            /* Read in fixed-sized portion of driver info block */
            p = dbuf;
            if(H5FD_set_eoa(lf, H5FD_MEM_SUPER, shared->driver_addr + H5F_DRVINFOBLOCK_HDR_SIZE) < 0)
                HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "set end of space allocation request failed")
            if(H5FD_read(lf, dxpl_id, H5FD_MEM_SUPER, shared->driver_addr, (size_t)H5F_DRVINFOBLOCK_HDR_SIZE, p) < 0)
                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to read driver information block")

            /* Version number */
            drv_vers = *p++;
            if(drv_vers != HDF5_DRIVERINFO_VERSION_0)
                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "bad driver information block version number")

            p += 3; /* reserved bytes */

            /* Driver info size */
            UINT32DECODE(p, drv_variable_size);

            /* Sanity check */
            HDassert(H5F_DRVINFOBLOCK_HDR_SIZE + drv_variable_size <= sizeof(dbuf));

            /* Driver name and/or version */
            HDstrncpy(drv_name, (const char *)p, (size_t)8);
            drv_name[8] = '\0';
            p += 8; /* advance past name/version */

            /* Check if driver matches driver information saved. Unfortunately, we can't push this
             * function to each specific driver because we're checking if the driver is correct.
             */
            if(!HDstrncmp(drv_name, "NCSAfami", (size_t)8) && HDstrcmp(lf->cls->name, "family"))
                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "family driver should be used")
            if(!HDstrncmp(drv_name, "NCSAmult", (size_t)8) && HDstrcmp(lf->cls->name, "multi"))
                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "multi driver should be used")

            /* Read in variable-sized portion of driver info block */
            if(H5FD_set_eoa(lf, H5FD_MEM_SUPER, shared->driver_addr + H5F_DRVINFOBLOCK_HDR_SIZE + drv_variable_size) < 0)
                HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "set end of space allocation request failed")
            if(H5FD_read(lf, dxpl_id, H5FD_MEM_SUPER, shared->driver_addr + H5F_DRVINFOBLOCK_HDR_SIZE, drv_variable_size, p) < 0)
                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to read file driver information")

            /* Decode driver information */
            if(H5FD_sb_decode(lf, drv_name, p) < 0)
                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to decode driver information")
        } /* end if */
    } /* end if */
    else {
        uint32_t computed_chksum;       /* Computed checksum  */
        uint32_t read_chksum;           /* Checksum read from file  */

        /* Size of file addresses */
        sizeof_addr = *p++;
        if(sizeof_addr != 2 && sizeof_addr != 4 &&
                sizeof_addr != 8 && sizeof_addr != 16 && sizeof_addr != 32)
            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad byte number in an address")
        if(H5P_set(c_plist, H5F_CRT_ADDR_BYTE_NUM_NAME, &sizeof_addr) < 0)
            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set byte number in an address")
        shared->sizeof_addr = sizeof_addr;  /* Keep a local copy also */

        /* Size of file sizes */
        sizeof_size = *p++;
        if(sizeof_size != 2 && sizeof_size != 4 &&
                sizeof_size != 8 && sizeof_size != 16 && sizeof_size != 32)
            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad byte number for object size")
        if(H5P_set(c_plist, H5F_CRT_OBJ_BYTE_NUM_NAME, &sizeof_size) < 0)
            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set byte number for object size")
        shared->sizeof_size = sizeof_size;  /* Keep a local copy also */

        /* File status flags (not really used yet) */
        shared->status_flags = *p++;
        if(shared->status_flags & ~H5F_SUPER_ALL_FLAGS)
            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad flag value for superblock")

        /* Base, superblock extension, end of file & root group object header addresses */
        H5F_addr_decode(f, (const uint8_t **)&p, &shared->base_addr/*out*/);
        H5F_addr_decode(f, (const uint8_t **)&p, &shared->extension_addr/*out*/);
        H5F_addr_decode(f, (const uint8_t **)&p, &stored_eoa/*out*/);
        H5F_addr_decode(f, (const uint8_t **)&p, &shared->root_addr/*out*/);

        /* Compute checksum for superblock */
        computed_chksum = H5_checksum_metadata(sbuf, (size_t)(p - sbuf), 0);

        /* Decode checksum */
        UINT32DECODE(p, read_chksum);

        /* Verify correct checksum */
        if(read_chksum != computed_chksum)
            HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "bad checksum on driver information block")

        /*
         * Check if superblock address is different from base address and
         * adjust base address and "end of address" address if so.
         */
        if(!H5F_addr_eq(abs_super_addr, shared->base_addr)) {
            /* Check if the superblock moved earlier in the file */
            if(H5F_addr_lt(abs_super_addr, shared->base_addr))
                stored_eoa -= (shared->base_addr - abs_super_addr);
            else
                /* The superblock moved later in the file */
                stored_eoa += (abs_super_addr - shared->base_addr);

            shared->base_addr = abs_super_addr;
        } /* end if */

        /* Set the base address for the file in the VFD now, after adjusting
         *  space for possible offsets of the HDF5 data in the file.
         */
        if(H5FD_set_base_addr(lf, shared->base_addr) < 0)
            HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "failed to set base address for file driver")
    } /* end else */

    /*
     * The user-defined data is the area of the file before the base
     * address.
     */
    if(H5P_set(c_plist, H5F_CRT_USER_BLOCK_NAME, &shared->base_addr) < 0)
        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set userblock size")

    /*
     * Make sure that the data is not truncated. One case where this is
     * possible is if the first file of a family of files was opened
     * individually.
     */
    if(HADDR_UNDEF == (eof = H5FD_get_eof(lf)))
        HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to determine file size")
    /* (Account for the stored EOA being absolute offset -QAK) */
    if((eof + H5F_BASE_ADDR(f)) < stored_eoa)
        HGOTO_ERROR(H5E_FILE, H5E_TRUNCATED, FAIL, "truncated file")

    /*
     * Tell the file driver how much address space has already been
     * allocated so that it knows how to allocate additional memory.
     */
    /* (Account for the stored EOA being absolute offset -NAF) */
    if(H5FD_set_eoa(lf, H5FD_MEM_SUPER, stored_eoa - H5F_BASE_ADDR(f)) < 0)
        HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to set end-of-address marker for file")

    /* Read the file's superblock extension, if there is one. */
    if(H5F_addr_defined(shared->extension_addr)) {
        H5O_loc_t ext_loc;      /* "Object location" for superblock extension */
        H5O_btreek_t btreek;    /* v1 B-tree 'K' value message from superblock extension */
        H5O_drvinfo_t drvinfo;  /* Driver info message from superblock extension */
        htri_t status;          /* Status for message existing */

        /* Sanity check - superblock extension should only be defined for
         *      superblock version >= 2.
         */
        HDassert(super_vers >= HDF5_SUPERBLOCK_VERSION_2);

        /* Check for superblock extension being located "outside" the stored
         *      'eoa' value, which can occur with the split/multi VFD.
         */
        if(H5F_addr_gt(shared->extension_addr, stored_eoa)) {
            /* Set the 'eoa' for the object header memory type large enough
             *  to give some room for a reasonably sized superblock extension.
             *  (This is _rather_ a kludge -QAK)
             */
            if(H5FD_set_eoa(lf, H5FD_MEM_OHDR, (haddr_t)(shared->extension_addr + 1024)) < 0)
                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to set end-of-address marker for file")
        } /* end if */

        /* Open the superblock extension */
	if(H5F_super_ext_open(f, &ext_loc) < 0)
            HGOTO_ERROR(H5E_FILE, H5E_CANTOPENOBJ, FAIL, "unable to start file's superblock extension")

        /* Check for the extension having a 'driver info' message */
        if((status = H5O_msg_exists(&ext_loc, H5O_DRVINFO_ID, dxpl_id)) < 0)
            HGOTO_ERROR(H5E_FILE, H5E_CANTGET, FAIL, "unable to read object header")
        if(status) {
            /* Retrieve the 'driver info' structure */
            if(NULL == H5O_msg_read(&ext_loc, H5O_DRVINFO_ID, &drvinfo, dxpl_id))
                HGOTO_ERROR(H5E_FILE, H5E_CANTGET, FAIL, "driver info message not present")

            /* Check if driver matches driver information saved. Unfortunately, we can't push this
             * function to each specific driver because we're checking if the driver is correct.
             */
            if(!HDstrncmp(drvinfo.name, "NCSAfami", (size_t)8) && HDstrcmp(lf->cls->name, "family"))
                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "family driver should be used")
            if(!HDstrncmp(drvinfo.name, "NCSAmult", (size_t)8) && HDstrcmp(lf->cls->name, "multi"))
                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "multi driver should be used")

            /* Decode driver information */
            if(H5FD_sb_decode(lf, drvinfo.name, drvinfo.buf) < 0)
                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to decode driver information")

            /* Reset driver info message */
            H5O_msg_reset(H5O_DRVINFO_ID, &drvinfo);
        } /* end if */

        /* Read in the shared OH message information if there is any */
        if(H5SM_get_info(&ext_loc, c_plist, dxpl_id) < 0)
            HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to read SOHM table information")

        /* Check for the extension having a 'v1 B-tree "K"' message */
        if((status = H5O_msg_exists(&ext_loc, H5O_BTREEK_ID, dxpl_id)) < 0)
            HGOTO_ERROR(H5E_FILE, H5E_CANTGET, FAIL, "unable to read object header")
        if(status) {
            /* Retrieve the 'v1 B-tree "K"' structure */
            if(NULL == H5O_msg_read(&ext_loc, H5O_BTREEK_ID, &btreek, dxpl_id))
                HGOTO_ERROR(H5E_FILE, H5E_CANTGET, FAIL, "v1 B-tree 'K' info message not present")

            /* Set non-default v1 B-tree 'K' value info from file */
            shared->btree_k[H5B_CHUNK_ID] = btreek.btree_k[H5B_CHUNK_ID];
            shared->btree_k[H5B_SNODE_ID] = btreek.btree_k[H5B_SNODE_ID];
            shared->sym_leaf_k = btreek.sym_leaf_k;

            /* Set non-default v1 B-tree 'K' values in the property list */
            if(H5P_set(c_plist, H5F_CRT_BTREE_RANK_NAME, btreek.btree_k) < 0)
                HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set rank for btree internal nodes")
            if(H5P_set(c_plist, H5F_CRT_SYM_LEAF_NAME, &btreek.sym_leaf_k) < 0)
                HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set rank for symbol table leaf nodes")
        } /* end if */
        else {
            /* No non-default v1 B-tree 'K' value info in file, use defaults */
            shared->btree_k[H5B_CHUNK_ID] = HDF5_BTREE_CHUNK_IK_DEF;
            shared->btree_k[H5B_SNODE_ID] = HDF5_BTREE_SNODE_IK_DEF;
            shared->sym_leaf_k = H5F_CRT_SYM_LEAF_DEF;
        } /* end if */

        /* Close superblock extension */
	if(H5F_super_ext_close(f, &ext_loc) < 0)
	    HGOTO_ERROR(H5E_FILE, H5E_CANTRELEASE, FAIL, "unable to close file's superblock extension")
    } /* end if */

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5F_super_read() */


/*-------------------------------------------------------------------------
 * Function:    H5F_super_init
 *
 * Purpose:     Allocates the superblock for the file and initializes
 *              information about the superblock in memory.  Writes extension
 *              messages if any are needed.
 *
 * Return:      Success:        SUCCEED
 *              Failure:        FAIL
 *
 * Programmer:  Quincey Koziol
 *              koziol@ncsa.uiuc.edu
 *              Sept 15, 2003
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5F_super_init(H5F_t *f, hid_t dxpl_id)
{
    H5P_genplist_t *plist;              /* File creation property list */
    hsize_t         userblock_size;     /* Size of userblock, in bytes */
    hsize_t         superblock_size;    /* Size of superblock, in bytes */
    size_t          driver_size;        /* Size of driver info block (bytes) */
    unsigned        super_vers;         /* Superblock version */
    haddr_t         super_addr;         /* Address of superblock */
    hbool_t         need_ext;           /* Whether the superblock extension is needed */
    herr_t          ret_value = SUCCEED;

    FUNC_ENTER_NOAPI(H5F_super_init, FAIL)

    /* Get the shared file creation property list */
    if(NULL == (plist = (H5P_genplist_t *)H5I_object(f->shared->fcpl_id)))
        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a property list")

    /*
     * The superblock starts immediately after the user-defined
     * header, which we have already insured is a proper size. The
     * base address is set to the same thing as the superblock for
     * now.
     */
    if(H5P_get(plist, H5F_CRT_USER_BLOCK_NAME, &userblock_size) < 0)
        HGOTO_ERROR(H5E_FILE, H5E_CANTGET, FAIL, "unable to get userblock size")
    f->shared->base_addr = userblock_size;
    f->shared->status_flags = 0;

    /* Reserve space for the userblock */
    if(H5FD_set_eoa(f->shared->lf, H5FD_MEM_SUPER, userblock_size) < 0)
        HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to set EOA value for userblock")

    /* Set the base address for the file in the VFD now, after allocating
     *  space for userblock.
     */
    if(H5FD_set_base_addr(f->shared->lf, f->shared->base_addr) < 0)
        HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "failed to set base address for file driver")

    /* Grab superblock version from property list */
    if(H5P_get(plist, H5F_CRT_SUPER_VERS_NAME, &super_vers) < 0)
        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get superblock version")

    /* Compute the size of the superblock */
    superblock_size = H5F_SUPERBLOCK_SIZE(super_vers, f);

    /* Compute the size of the driver information block */
    H5_ASSIGN_OVERFLOW(driver_size, H5FD_sb_size(f->shared->lf), hsize_t, size_t);
    if(driver_size > 0) {
        driver_size += H5F_DRVINFOBLOCK_HDR_SIZE;

        /*
         * The file driver information block begins immediately after the
         * superblock. (relative to base address in file)
         */
        f->shared->driver_addr = superblock_size;
    } /* end if */

    /*
     * Allocate space for the userblock, superblock & driver info blocks.
     * We do it with one allocation request because the userblock and
     * superblock need to be at the beginning of the file and only the first
     * allocation request is required to return memory at format address zero.
     */
    if(super_vers < HDF5_SUPERBLOCK_VERSION_2)
        superblock_size += driver_size;
    super_addr = H5MF_alloc(f, H5FD_MEM_SUPER, dxpl_id, superblock_size);
    if(HADDR_UNDEF == super_addr)
        HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to allocate file space for userblock and/or superblock")
    if(0 != super_addr)
        HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "file driver failed to allocate userblock and/or superblock at address zero")

    /*
     * Determine if we will need a superblock extension
     */

    /* Files with SOHM indices always need the superblock extension */
    if(f->shared->sohm_nindexes > 0) {
        HDassert(super_vers >= HDF5_SUPERBLOCK_VERSION_2);
        need_ext = TRUE;
    } /* end if */
    /* If we're going to use a version of the superblock format which allows
     *  for the superblock extension, check for non-default values to store
     *  in it.
     */
    else if(super_vers >= HDF5_SUPERBLOCK_VERSION_2) {
        /* Check for non-default v1 B-tree 'K' values to store */
        if(f->shared->btree_k[H5B_SNODE_ID] != HDF5_BTREE_SNODE_IK_DEF ||
                f->shared->btree_k[H5B_CHUNK_ID] != HDF5_BTREE_CHUNK_IK_DEF ||
                f->shared->sym_leaf_k != H5F_CRT_SYM_LEAF_DEF)
            need_ext = TRUE;
        /* Check for driver info to store */
        else if(driver_size > 0)
            need_ext = TRUE;
        else
            need_ext = FALSE;
    } /* end if */
    else
        need_ext = FALSE;

    /* Create the superblock extension for "extra" superblock data, if necessary. */
    if(need_ext) {
        H5O_loc_t       ext_loc;            /* Superblock extension object location */

        /* The superblock extension isn't actually a group, but the
         * default group creation list should work fine.
         * If we don't supply a size for the object header, HDF5 will
         * allocate H5O_MIN_SIZE by default.  This is currently
         * big enough to hold the biggest possible extension, but should
         * be tuned if more information is added to the superblock
         * extension.
         */
	if(H5F_super_ext_create(f, dxpl_id, &ext_loc) < 0)
            HGOTO_ERROR(H5E_FILE, H5E_CANTRELEASE, FAIL, "unable to start file's superblock extension")

        /* Create the Shared Object Header Message table and register it with
         *      the metadata cache, if this file supports shared messages.
         */
        if(f->shared->sohm_nindexes > 0) {
            /* Initialize the shared message code & write the SOHM message to the extension */
            if(H5SM_init(f, plist, &ext_loc, dxpl_id) < 0)
                HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to create SOHM table")
        } /* end if */

        /* Check for non-default v1 B-tree 'K' values to store */
        if(f->shared->btree_k[H5B_SNODE_ID] != HDF5_BTREE_SNODE_IK_DEF ||
                f->shared->btree_k[H5B_CHUNK_ID] != HDF5_BTREE_CHUNK_IK_DEF ||
                f->shared->sym_leaf_k != H5F_CRT_SYM_LEAF_DEF) {
            H5O_btreek_t btreek;        /* v1 B-tree 'K' value message for superblock extension */

            /* Write v1 B-tree 'K' value information to the superblock extension */
            btreek.btree_k[H5B_CHUNK_ID] = f->shared->btree_k[H5B_CHUNK_ID];
            btreek.btree_k[H5B_SNODE_ID] = f->shared->btree_k[H5B_SNODE_ID];
            btreek.sym_leaf_k = f->shared->sym_leaf_k;
            if(H5O_msg_create(&ext_loc, H5O_BTREEK_ID, H5O_MSG_FLAG_CONSTANT | H5O_MSG_FLAG_DONTSHARE, H5O_UPDATE_TIME, &btreek, dxpl_id) < 0)
                HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to update v1 B-tree 'K' value header message")
        } /* end if */

        /* Check for driver info to store */
        if(driver_size > 0) {
            H5O_drvinfo_t drvinfo;      /* Driver info */
            uint8_t dbuf[H5F_MAX_DRVINFOBLOCK_SIZE];  /* Driver info block encoding buffer */

            /* Sanity check */
            HDassert(driver_size <= H5F_MAX_DRVINFOBLOCK_SIZE);

            /* Encode driver-specific data */
            if(H5FD_sb_encode(f->shared->lf, drvinfo.name, dbuf) < 0)
                HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to encode driver information")

            /* Write driver info information to the superblock extension */
            drvinfo.len = driver_size;
            drvinfo.buf = dbuf;
            if(H5O_msg_create(&ext_loc, H5O_DRVINFO_ID, H5O_MSG_FLAG_DONTSHARE, H5O_UPDATE_TIME, &drvinfo, dxpl_id) < 0)
                HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to update driver info header message")
        } /* end if */

        /* Close superblock extension */
	if(H5F_super_ext_close(f, &ext_loc) < 0)
	    HGOTO_ERROR(H5E_FILE, H5E_CANTRELEASE, FAIL, "unable to close file's superblock extension")
    } /* end if */

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5F_super_init() */


/*-------------------------------------------------------------------------
 * Function:    H5F_super_write
 *
 * Purpose:     Writes the superblock for the file.
 *
 * Return:      Success:        SUCCEED
 *              Failure:        FAIL
 *
 * Programmer:  Bill Wendling
 *              wendling@ncsa.uiuc.edu
 *              Sept 12, 2003
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5F_super_write(H5F_t *f, hid_t dxpl_id)
{
    H5P_genplist_t *plist;                      /* File creation property list */
    uint8_t         buf[H5F_MAX_SUPERBLOCK_SIZE + H5F_MAX_DRVINFOBLOCK_SIZE];  /* Superblock & driver info blockencoding buffer */
    uint8_t        *p;                          /* Ptr into encoding buffer */
    haddr_t         rel_eoa;                    /* Relative EOA for file */
    size_t          superblock_size;            /* Size of superblock, in bytes */
    size_t          driver_size;                /* Size of driver info block (bytes)*/
    unsigned        super_vers;                 /* Superblock version              */
    herr_t          ret_value = SUCCEED;

    FUNC_ENTER_NOAPI(H5F_super_write, FAIL)

    /* Get the shared file creation property list */
    if(NULL == (plist = (H5P_genplist_t *)H5I_object(f->shared->fcpl_id)))
        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a property list")

    /* Grab values from property list */
    if(H5P_get(plist, H5F_CRT_SUPER_VERS_NAME, &super_vers) < 0)
        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get superblock version")

    /* Encode the common portion of the file superblock for all versions */
    p = buf;
    HDmemcpy(p, H5F_SIGNATURE, (size_t)H5F_SIGNATURE_LEN);
    p += H5F_SIGNATURE_LEN;
    *p++ = (uint8_t)super_vers;

    /* Check for older version of superblock format */
    if(super_vers < HDF5_SUPERBLOCK_VERSION_2) {
        *p++ = (uint8_t)HDF5_FREESPACE_VERSION;     /* (hard-wired) */
        *p++ = (uint8_t)HDF5_OBJECTDIR_VERSION;     /* (hard-wired) */
        *p++ = 0;   /* reserved*/

        *p++ = (uint8_t)HDF5_SHAREDHEADER_VERSION;  /* (hard-wired) */
        HDassert(H5F_SIZEOF_ADDR(f) <= 255);
        *p++ = (uint8_t)H5F_SIZEOF_ADDR(f);
        HDassert(H5F_SIZEOF_SIZE(f) <= 255);
        *p++ = (uint8_t)H5F_SIZEOF_SIZE(f);
        *p++ = 0;   /* reserved */

        UINT16ENCODE(p, f->shared->sym_leaf_k);
        UINT16ENCODE(p, f->shared->btree_k[H5B_SNODE_ID]);
        UINT32ENCODE(p, (uint32_t)f->shared->status_flags);

        /*
         * Versions of the superblock >0 have the indexed storage B-tree
         * internal 'K' value stored
         */
        if(super_vers > HDF5_SUPERBLOCK_VERSION_DEF) {
            UINT16ENCODE(p, f->shared->btree_k[H5B_CHUNK_ID]);
            *p++ = 0;   /*reserved */
            *p++ = 0;   /*reserved */
        } /* end if */

        H5F_addr_encode(f, &p, f->shared->base_addr);
        H5F_addr_encode(f, &p, f->shared->extension_addr);
        rel_eoa = H5FD_get_eoa(f->shared->lf, H5FD_MEM_SUPER);
        H5F_addr_encode(f, &p, (rel_eoa + f->shared->base_addr));
        H5F_addr_encode(f, &p, f->shared->driver_addr);

        /* Encode the root group object entry, including the cached stab info */
        if(H5G_root_ent_encode(f, &p) < 0)
            HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to encode root group information")

        /* Encode the driver information block. */
        H5_ASSIGN_OVERFLOW(driver_size, H5FD_sb_size(f->shared->lf), hsize_t, size_t);

        /* Checking whether driver block address is defined here is to handle backward
         * compatibility.  If the file was created with v1.6 library or earlier and no
         * driver info block was written in the superblock, we don't write it either even
         * though there's some driver info.  Otherwise, the driver block extended will
         * overwrite the (meta)data right after the superblock. This situation happens to
         * the family driver particularly.  SLU - 2009/3/24 
         */
        if(driver_size > 0 && H5F_addr_defined(f->shared->driver_addr)) {
            char driver_name[9];    /* Name of driver, for driver info block */
            uint8_t *dbuf = p;      /* Pointer to beginning of driver info */

            /* Encode the driver information block */
            *p++ = HDF5_DRIVERINFO_VERSION_0; /* Version */
            *p++ = 0; /* reserved */
            *p++ = 0; /* reserved */
            *p++ = 0; /* reserved */

            /* Driver info size, excluding header */
            UINT32ENCODE(p, driver_size);

            /* Encode driver-specific data */
            if(H5FD_sb_encode(f->shared->lf, driver_name, dbuf + H5F_DRVINFOBLOCK_HDR_SIZE) < 0)
                HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to encode driver information")

            /* Store driver name (set in 'H5FD_sb_encode' call above) */
            HDmemcpy(p, driver_name, (size_t)8);

            /* Advance buffer pointer past name & variable-sized portion of driver info */
            /* (for later use in computing the superblock size) */
            p += 8 + driver_size;
        } /* end if */
    } /* end if */
    else {
        uint32_t        chksum;                 /* Checksum temporary variable      */
        H5O_loc_t       *root_oloc;             /* Pointer to root group's object location */

        /* Size of file addresses & offsets, and status flags */
        HDassert(H5F_SIZEOF_ADDR(f) <= 255);
        *p++ = (uint8_t)H5F_SIZEOF_ADDR(f);
        HDassert(H5F_SIZEOF_SIZE(f) <= 255);
        *p++ = (uint8_t)H5F_SIZEOF_SIZE(f);
        *p++ = f->shared->status_flags;

        /* Base, superblock extension & end of file addresses */
        H5F_addr_encode(f, &p, f->shared->base_addr);
        H5F_addr_encode(f, &p, f->shared->extension_addr);
        rel_eoa = H5FD_get_eoa(f->shared->lf, H5FD_MEM_SUPER);
        H5F_addr_encode(f, &p, (rel_eoa + f->shared->base_addr));

        /* Retrieve information for root group */
        if(NULL == (root_oloc = H5G_oloc(f->shared->root_grp)))
            HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to retrieve root group information")

        /* Encode address of root group's object header */
        H5F_addr_encode(f, &p, root_oloc->addr);

        /* Compute superblock checksum */
        chksum = H5_checksum_metadata(buf, (H5F_SUPERBLOCK_SIZE(super_vers, f) - H5F_SIZEOF_CHKSUM), 0);

        /* Superblock checksum */
        UINT32ENCODE(p, chksum);

        /* Sanity check */
        HDassert((size_t)(p - buf) == H5F_SUPERBLOCK_SIZE(super_vers, f));
    } /* end else */

    /* Retrieve the total size of the superblock info */
    H5_ASSIGN_OVERFLOW(superblock_size, (p - buf), int, size_t);

    /* Double check we didn't overrun the block (unlikely) */
    HDassert(superblock_size <= sizeof(buf));

    /* Write superblock (always at relative offset 0) */
    if(H5FD_write(f->shared->lf, dxpl_id, H5FD_MEM_SUPER, (haddr_t)0, superblock_size, buf) < 0)
        HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "unable to write superblock")

    /* Check for newer version of superblock format & superblock extension */
    if(super_vers >= HDF5_SUPERBLOCK_VERSION_2 && H5F_addr_defined(f->shared->extension_addr)) {
        /* Check for driver info message */
        H5_ASSIGN_OVERFLOW(driver_size, H5FD_sb_size(f->shared->lf), hsize_t, size_t);
        if(driver_size > 0) {
            H5O_loc_t ext_loc;      /* "Object location" for superblock extension */
            H5O_drvinfo_t drvinfo;      /* Driver info */
            uint8_t dbuf[H5F_MAX_DRVINFOBLOCK_SIZE];  /* Driver info block encoding buffer */

            /* Sanity check */
            HDassert(driver_size <= H5F_MAX_DRVINFOBLOCK_SIZE);

            /* Encode driver-specific data */
            if(H5FD_sb_encode(f->shared->lf, drvinfo.name, dbuf) < 0)
                HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to encode driver information")

            /* Open the superblock extension */
            if(H5F_super_ext_open(f, &ext_loc) < 0)
                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENOBJ, FAIL, "unable to start file's superblock extension")

            /* Write driver info information to the superblock extension */
            drvinfo.len = driver_size;
            drvinfo.buf = dbuf;
            if(H5O_msg_write(&ext_loc, H5O_DRVINFO_ID, H5O_MSG_FLAG_DONTSHARE, H5O_UPDATE_TIME, &drvinfo, dxpl_id) < 0)
                HGOTO_ERROR(H5E_FILE, H5E_CANTSET, FAIL, "unable to update driver info header message")

            /* Close superblock extension */
	    if(H5F_super_ext_close(f, &ext_loc) < 0)
		HGOTO_ERROR(H5E_FILE, H5E_CANTRELEASE, FAIL, "unable to close file's superblock extension")
        } /* end if */
    } /* end if */

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5F_super_write() */


/*-------------------------------------------------------------------------
 * Function:    H5F_super_ext_size
 *              Get storage size of the superblock extension
 *
 * Return:      Success:        non-negative on success
 *              Failure:        Negative
 *
 * Programmer:  Vailin Choi
 *              July 11, 2007
 *-------------------------------------------------------------------------
 */
herr_t
H5F_super_ext_size(H5F_t *f, hid_t dxpl_id, hsize_t *super_ext_size)
{
    H5O_loc_t ext_loc;                  /* "Object location" for superblock extension */
    H5O_info_t oinfo;                   /* Object info for superblock extension */
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_NOAPI(H5F_super_ext_size, FAIL)

    /* Sanity check */
    HDassert(f);
    HDassert(super_ext_size);

    /* Set up "fake" object location for superblock extension */
    H5O_loc_reset(&ext_loc);
    ext_loc.file = f;
    ext_loc.addr = f->shared->extension_addr;

    /* Get object header info for superblock extension */
    if(H5O_get_info(&ext_loc, dxpl_id, FALSE, &oinfo) < 0)
	HGOTO_ERROR(H5E_FILE, H5E_CANTGET, FAIL, "unable to retrieve superblock extension info")

    /* Set the superblock extension size */
    *super_ext_size = oinfo.hdr.space.total;

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* H5F_super_ext_size() */